1. Incremental encoder: Convert displacement into periodic electrical signal, and then convert this electrical signal into counting pulses, and the number of pulses indicates displacement.
2. Absolute encoder: Because each position is absolutely unique, it is anti-interference and does not need power-off memory, so it has been widely used in angle and length measurement and positioning control of various industrial systems.
Second, the principle is different.
1. Incremental encoder: One edge of a code wheel has an equiangular gap (divided into transparent and opaque parts), and the light source and photosensitive elements are installed on both sides of the encoder. When the code wheel rotates with the working shaft, the light and shadow will change every time a slot is rotated.
After shaping and amplification, an electric pulse output signal with a certain amplitude and power can be obtained, and the number of pulses is equal to the number of rotating slots. The pulse signal is sent to the counter for counting, and the rotation angle of the disc can be known from the measured numbers.
2. Absolute encoder: Because of its high precision and many output bits, if parallel output is still used, then each output signal must be connected well. For more complicated situations, there are many cable cores, which brings a lot of inconvenience and reduces reliability.
So the absolute encoder is a multiple. The output type is generally serial output or bus output, and the serial output of German absolute encoder is the most commonly used SSI (synchronous serial output).
Extended data:
When the rotating shaft of the incremental encoder rotates, there is a corresponding pulse output. The reverse judgment circuit and counter are used to judge the rotation direction and increase or decrease the number of pulses. The starting point of counting can be set at will, realizing infinite accumulation and multi-period measurement.
It can also use the Z signal of each transmitted pulse as the reference mechanical zero position. The number of pulses is determined by the number of rows in the encoder grating. Can a 90-degree phase difference be used to improve the resolution? Multiply the A and B signals by the original number of pulses or replace the high-resolution encoder.
Baidu encyclopedia-incremental encoder
Baidu encyclopedia-absolute encoder